Compositions based on isocyanate chemistry find utility as components in coatings, such as, for example, paints, primers, and the like. Isocyanate-based coating compositions may include, for example, polyurethane coatings formed from resins comprising components, such as, for example, diisocyanates, polyisocyanates, and/or isocyanate reaction products. These resins may cure by various mechanisms so that covalent bonds form between the resin components, thereby producing a cross-linked polymer network.
Moisture-curable (i.e., moisture-curing) coatings based on isocyanate-functional resins represent one type of isocyanate-based coating technology. Isocyanate-based moisture-curable coatings may generally comprise, for example, diisocyanates, polyisocyanates, and/or isocyanate reaction products having free isocyanate groups that may react with atmospheric moisture to produce insoluble and relatively high molecular weight cross-linked polyurethane networks, which may form the structural component of the cured coatings. As used herein, the term “polyurethane” means polymeric or oligomeric materials comprising
The curing process may involve the reaction of free isocyanate groups with atmospheric water molecules to form a carbamic acid intermediate that decomposes into amine groups and carbon dioxide. The amine groups formed in situ by way of the isocyanate-water reaction may react with additional free isocyanate groups to form urea crosslinks between resin components. In this manner, a resin may be applied to a substrate, exposed to ambient atmosphere, and cure to form a polyurethane coating on the substrate.